Early J supported a variety of trains that are not currently supported
(and which, sadly, can't be re-enabled using a foreign).

That said, you can still achieve their results using explicit definitions.

However, in explicit definitions, some names are reserved: m n u v x y

So I would first use a different name than 'v':

   V=:+*:

WIth that out of the way, I can go:

   incrby=:1 :'(u (&>) i.) y'
   V incrby 6
6 7 10 15 22 31

Thanks,

-- 
Raul

On Fri, May 31, 2019 at 2:23 PM Ulrich Vollert <[email protected]> wrote:
>
> Norman Thompson defines a verb
>
> v =: +*:
>
> which computes n(n+1).
>
> Now
>
> (v i.) 6
>
> gives y + i*i (i=0,1,..,y)
>
> 6 7 10 15 22 31
>
> and then he says: „This can be generalized by defining an adverb:
>
> incrby =: (&>) i.
> v incrby 6
> 6 7 10 15 22 31
> "
>
> which I really don’t understand and which is a syntax error in 
> j807/j64/darwin.
>
>
> > Am 31.05.2019 um 20:05 schrieb 'Pascal Jasmin' via Programming 
> > <[email protected]>:
> >
> > can you tell us what the function is expected to do?
> > &> is an unboxing adverb
> > (a v) is a syntax error.  But perhaps an early version of J, it wasn't.
> >
> >
> >    On Friday, May 31, 2019, 2:00:00 p.m. EDT, Ulrich Vollert 
> > <[email protected]> wrote:
> >
> > Hello,
> >
> > I am reading „J: The natural language for analytic computing“ and on page 
> > 47 the author defines an adverb
> >
> >     incrby =: (&>) i.
> >
> > which leads to a syntax error if I try to define it.
> >
> > Any hint what is going on?
> >
> > Regards,
> > Ulrich
> >
> >
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